Power supply control devices are provided in vehicles to control the supply of power to a load from a direct-current power source to a load (See JP 2014-216765A, for example). In the power supply control device disclosed in JP 2014-216765A, a direct-current power source is connected to a current output end of a first switch, and a load is connected to the current input end of the first switch. The supply of power from the direct-current power source to the load is controlled by the first switch being switched to ON or OFF.
In the power supply control device disclosed in JP 2014-216765A, a series arrangement of a second switch a resistor in a series circuit is connected in parallel to the first switch, and the voltage of the current output end of the first switch is detected.
If the current output end of the first switch is an open circuit, that is, if a conductor between the first switch and the load is disconnected, when the first switch and the second switch are respectively OFF and ON, the detected voltage value is the output voltage value of the direct-current power source, because no current flows through the resistor. A predetermined voltage is set to a voltage that is lower than the output voltage of the direct-current power source. If the detected voltage value is greater than or equal to the predetermined voltage in a state in which the first switch and the second switch are respectively OFF and ON, an open circuit of the power output end of the first switch is detected.
In a case where the current input end and the current output end of the first switch have short-circuited, if the first switch and the second switch are both OFF, the detected voltage value is the output voltage value of the direct-current power source, and is great or equal to the predetermined voltage value. If the detected voltage value is greater than or equal to the predetermined voltage value in a state in which the first switch and the second switch are both OFF, a short circuit between the current input end and the current output end of the first switch is detected.
However, in the power supply control device disclosed in JP 2014-216765A, in one state depending on whether the first switch and second switch are ON or OFF, for example a state in which the first switch and the second switch are both OFF, neither an open circuit of the current output end of the first switch, nor a short circuit between the current input end and the current output end of the first switch, can be detected. For this reason, the power supply control device described in JP 2014-216765A has a problem in that an open circuit of the current output end of the first switch and a short circuit between the current input end and the current output end of the first switch cannot easily be detected.
The present disclosure has been made in view of such circumstances, and an objective thereof is to provide a power supply control device that can easily detect an open circuit of a current output end of a switch and a short circuit between a current input end and a current output end of a switch.